Spaghettifying DRAM

I cannot wait for the accompanying Black Hat talk. Christopher Domas is one of my absolute favorite all-time hackers. He does such a fantastic job of explaining his work. Some of my favorite talks of his:

- Psychological Warfare in Reverse Engineering https://www.youtube.com/watch?v=HlUe0TUHOIc

- The MoVfuscator https://www.youtube.com/watch?v=R7EEoWg6Ekk

- Hardware Backdoors in redacted x86 https://www.youtube.com/watch?v=jmTwlEh8L7g

This is all great to get full unfettered access to your own system, as life should be.

I’m sure Xbox and PlayStation security groups are a little nervous right now though. Getting ring-0 on those machines is near impossible, but once you do then everything else becomes wide open

When I started with computers, DRAM was understandable by a teenager: RAS, CAS, read, done.

Ok, the necessary refresh was always a little pain, but still something manageable.

Nowadays, I feel you need three PhD's to even bring up a micro with DRAM and don't get me started on the proprietary binary blobs necessary just for DRAM access. No wonder PSRAM is a thing.

The corollary is that it shouldn't be too surprising that this gigantic attack surface provides many opportunities. (Of course that doesn't mean it is easy to find them, hat tip to Christopher Domas, just that I expect there to be many more).

OK, so this works on AMD Jaguar according to the README. That's a architecture from 2013. There's notes about Zen 3 having a different base address for the memory controller registers, but that's it. What newer CPUs does attack actually work on?

I spaghettify my memory every time I write C code.

So on an affected system, ring 0 root has access to pretty much everything that was hidden in negative ring territory. The page is pretty quiet about what other processor families might be similar beyond this specific AMD16h (an older AMD low-power family)?

This is only applicable if you already have root (in order to get beyond that), right? It doesn't expose new risk of local privilege escalation?

This is so cool. Outside of a cool demo, and maybe some black hat type stuff, this is surely dangerous, a bad idea, and shouldn't be done in prod. But pure hacker ethos at its heart.

The big question is whether this can break out of KVM and whether it can be microrode patched / patched in any other way.

And whether it's really real in the first place.

I don't understand the threat model being attacked here. If you had physical DRAM access you could do all of this anyway right? And I would assume that an unprivileged user would not have write access to the DRAM controller registers?

I really hate to be that guy, but man, as someone who was and is a big Christopher Domas fan (and is way dumber than him, I mean, this stuff is seriously over my head)... it's been really disappointing to see him LLM'ing all the READMEs recently. They used to be a joy to read through, but now the Claudeisms made it such a slog I could barely get through a few paragraphs. I'm glad he's using the new tools to get even more cool stuff done, but I wish he'd have gone for a human writeup at the end.

Fascinating. So what is the DCT swizzling functionality designed for in the hardware originally?

On IntelME/AMD PSP:

https://jxself.org/titanic.shtml

He did it well. On "security", the author loves more to own his code/adata than anything. as did the PDP10/ITS hackers.

Holy shit, Christopher Domas is back. I remember watching his Defcon talks on x86 shenanigans[^1][^2] and being amazed at what he's been able to discover. Then he got whisked away by Intel and now drops this. I'm excited.

[^1]: https://www.youtube.com/watch?v=XH0F9r0siTI

[^2]: https://www.youtube.com/watch?v=jmTwlEh8L7g

The researcher behind this is obviously highly knowledgeable in reverse engineering CPUs to the tune it reminds me of the dwarves digging in Moria...

But why on earth do they have to use AI to write their writeups?!

This is the level of access the rightful owner of a computer should have to his own system.

He should also be able to fuse away this access forever, to be fair. But out of the box, when I get a new laptop, I should be able to read and write every byte of DRAM.

This is probably very interesting, but does it really have to be explained with a solid wall of AI slop writing?

Opus refuses to discuss this at all. Make of that what you will.

Holy crap. This is like a software-reachable version of the dynamic memory aliasing hardware attack demonstrated by https://batteringram.eu/

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Could someone ELI5 please? Context, achievement, scope, consequences?

Skitter creek bath salts... Or SCBS Guess there'll be a talk called Secure Computing BullShit in the next Blackhat conf! I'll be eagerly waiting for it! :)